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Don't leave a trace: Private Browsing in Firefox

Today, a major feature was added to the pre-release versions of Firefox 3.1, called Private Browsing.  I've been working for quite some time on this, so I thought it may be a good time to write about what this feature is and how to use it.

As you may know, while you browse the web, your browser usually records a lot of data which will later be used to improve your browsing experience.  For example, it records a history of all the web pages you have visited, so that later if you need help remembering a site you visited a while back, it can assist you in finding that site.  Now, that is great, but there is a downside: those data can be used to trace your online activities.  For example, if your coworker sits at your computer, she can view all of your browsing history, which may not be what you want.

Suppose you're doing something online, and you don't want your coworkers know about it.  An example scenario would be looking for a new employer while at work!  One option would be to do your work, and then clear the data that Firefox has stored for you, such as history, cookies, cache, ....  But the problem is that this action will also remove the parts of your online activities data which you don't want to hide, so the history that Firefox records can no longer be used to find a web site you had visited a month before.  Private Browsing will help you here.

Private Browsing aims to help you make sure that your web browsing activities don't leave any trace on your own computer.  It is very important to note that Private Browsing is not a tool to keep you anonymous from websites or your ISP, or for example protect you from all kinds of spyware applications which use sophisticated techniques to intercept your online traffic.  Private Browsing is only about making sure that Firefox doesn't store any data which can be used to trace your online activities, no more, no less.

So how does one actually use this feature?  It couldn't be simpler!  To start, just select Private Browsing from the Tools menu.

To start, just select Private Browsing from the Tools menu.

You will see a dialog box which asks you whether you want to save and close all of your current windows and tabs, and start the Private Browsing mode.  Click Start Private Browsing to start your private session.

Click Start Private Browsing to start your private session.

After you do this, your non-private browsing session is closed and a new private session is opened, showing you the screen below.  (Before you mention, the ugly icon you see there is something I created as a placeholder!  This icon will be replaced in the final release of Firefox 3.1.)

Start of the Private Browsing mode

As you see, not much is different in the Firefox window inside the Private Browsing mode, except for the (Private Browsing) text added to the title bar at the top of the window.  That is intentional: after all, if you're doing something online that you don't want your coworkers to know about, you don't want to raise their attention with a big sign saying PRIVATE as they pass by and glance over your shoulder. 

At this stage, you can start browsing web sites, without ever having to worry that Firefox might store something on your computer which can be used to tell which pages you have visited.  Once you're done, just uncheck the same menu item in the Tools menu to close your private session.

Once you're done, just uncheck the same menu item in the Tools menu to close your private session.

 This action discards all of the data from your private session, and will restore your non-private browsing session, just like it was before entering the Private Browsing mode.

This action will restore your non-private browsing session, just like it was before entering the Private Browsing mode.

Now, as I mentioned at the top of this post, this feature is available in pre-release versions of Firefox 3.1 (what we geeks call nightly builds).  This feature will be included in Firefox 3.1 Beta 2 which will be released soon, so if you want to try it, you can give it a shot then.  And of course, it will appear in the final release of Firefox 3.1, so if you're not the type who test beta software, you can wait until Firefox 3.1 is released.

Update:  As many people seem interested in knowing this, there is a way to make Firefox always start in Private Browsing mode.  Go to the about:config page, click I'll be careful, I promise, type browser.privatebrowsing.autostart in the Filter text box, double click the entry to make its value true.  After doing this, the next time you start Firefox, it will start in private browsing mode automatically.  To turn this off, use the same steps to change the value of this preference to false.  There is a plan to provide an easier method to set this option in the final release of Firefox 3.1.

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Mozilla firefox introduces private mode

Firefox users finally have the feature they were requesting for a long time. Pre-release of Firefox 3.1 Beta was done on 8th dec. This release includes, among many other features, an option to surf the web in Private mode.
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firefox 3.1でプライバシーモード実装

先日google chromeのシークレットモードについてレポしましたが、firefoxの最新バージョン、3.1のベータ版で同様の機能を持つプライバシーモードが実...

Don't leave a trace: Private Browsing in Firefox

Today, a major feature was added to the pre-release versions of Firefox 3.1, called Private Browsing. I've been working for quite some time on this, so I thought it may be a good time to write about what this feature is and how to use it.

As you may ...

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[...] preview release intended for developer testing and community feedback. New features include a private browsing mode, new functions that make it easy to remove specific portions of web history, a new javascript [...]

Pingback

[...] preview release intended for developer testing and community feedback. New features include a private browsing mode, new functions that make it easy to remove specific portions of web history, a new javascript [...]

Pingback

[...] preview release intended for developer testing and community feedback. New features include a private browsing mode, new functions that make it easy to remove specific portions of web history, a new javascript [...]

Pingback

[...] preview release intended for developer testing and community feedback. New features include a private browsing mode, new functions that make it easy to remove specific portions of web history, a new javascript [...]

Pingback

[...] preview release intended for developer testing and community feedback. New features include a private browsing mode, new functions that make it easy to remove specific portions of web history, a new javascript [...]

Pingback

[...] preview release intended for developer testing and community feedback. New features include a private browsing mode, new functions that make it easy to remove specific portions of web history, a new javascript [...]

Pingback

[...] preview release intended for developer testing and community feedback. New features include a private browsing mode, new functions that make it easy to remove specific portions of web history, a new javascript [...]

Pingback

[...] preview release intended for developer testing and community feedback. New features include a private browsing mode, new functions that make it easy to remove specific portions of web history, a new javascript [...]

Pingback

[...] preview release intended for developer testing and community feedback. New features include a private browsing mode, new functions that make it easy to remove specific portions of web history, a new javascript [...]

Pingback

[...] preview release intended for developer testing and community feedback. New features include a private browsing mode, new functions that make it easy to remove specific portions of web history, a new javascript [...]

Clarification

In your description above, you say:

This action discards all of the data from your private session, and will restore your non-private browsing session, just like it was before entering the Private Browsing mode.

This leads me to believe that data is at some point written to disk and then later "deleted". Can you clarify if this is, or is not, the case. If data is written during PB and then erased at the end, then this is no different than Clear Private Data function, and is not secure since the files can be recovered. I understood PB to mean that no data was ever written to disk (unless you download or open a file using a native application).

Please clarify.

Thanks

Re: Clarification

No, the data you're talking about is never written to disk during the private browsing mode.  By "discarding" I meant that Firefox clears them from main memory.
This way if your browser crashes during a private browisng session (or there is a power outage, or any other reason why Firefox would not be able to shut down clearly), then no traces of your browsing would remain on the hard disk of your computer.

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[...] preview release intended for developer testing and community feedback. New features include a private browsing mode, new functions that make it easy to remove specific portions of web history, a new javascript [...]

Active downloads are cancelled when exiting private browsing

When you quit private browsing, it's easy to forget if you have any downloads in progress. Any downloads which are in progress get canceled as well.

It would be useful to have some sort of warning when you try to quit private browsing:
eg.
"You have active downloads in progress. Are you SURE you want to quit private browsing at this time?"

Re: Active downloads are cancelled when exiting private browsing

We actually do show such a warning if the download is not resumable.  If it is, we just pause it silently, and restart it when you leave the private browsing mode.

Note: Something I didn't make

Note: Something I didn't make very clear is that I'm talking about when you "Stop Private Browsing" in the Tools menu, rather than quitting the browser altogether.

For "resumable" downloads I assume that you meant to say "when you re-enter private browsing mode"

Ah, that's interesting.  Yes,

Ah, that's interesting.  Yes, you're right; I guess we should prompt whether or not the download is resumable when leaving the private browsing mode.  I have filed a bug in the Mozilla bug database about this, and will work on fixing it.  Thanks for reporting this!

You're welcome, Just wanted

You're welcome,

Just wanted to clarify a couple of things about the comment you made earlier...

Referring to resumable downloads, you said: "If it is, we just pause it silently, and restart it when you leave the private browsing mode."

It occurred to me that a download which was started in "Private Browsing" is a private download, so IMHO should only be restarted when "re-entering" private mode, not when "leaving".

However, even if that was the case, does being able to restart it mean that some record of the partial download would have to exist in the non-private browser cache? It seems to me that this would defeat the purpose....

Re: You're welcome, Just wanted

I was talking about downloads started from the normal browsing session.  Downloads started from private browsing mode should either be cancelled at the end of that mode, or the user should wait for them to complete before leaving the private mode.  We can't store records of them so that they would be restarted when entering another private browsing mode session (and it doesn't make much sense since any private browsing session is isolated with regard to other such sessions.)

Perfect. That's all exactly

Perfect.

That's all exactly how I thought it should work.
(I had previously thought that you were talking about DL's started within private mode)

Thanks for the clarification.

I've never seen such a

I've never seen such a warning.

There may be a bug then,

There may be a bug then, because I've never seen such a warning.

Re: There may be a bug then

No, that probably means that you all of your downloads have been resumable.  Please note that most web downloads are resumable, so encountering an unresumable web download is an uncommon situation.

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[...] preview release intended for developer testing and community feedback. New features include a private browsing mode, new functions that make it easy to remove specific portions of web history, a new javascript [...]

help with private browsing

I won't need it or use it, and would love to know how to use about config or something to remove it from Tools menu with 3.5
please and much thanks!

Re: help with private browsing

Unfortunately, there is no way to remove this feature from the Tools menu.  But I suppose if you don't use it, you can simply ignore it, and it won't change any of the usual behavior of the browser.

Pingback

[...] preview release intended for developer testing and community feedback. New features include a private browsing mode, new functions that make it easy to remove specific portions of web history, a new javascript [...]

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[...] preview release intended for developer testing and community feedback. New features include a private browsing mode, new functions that make it easy to remove specific portions of web history, a new javascript [...]

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[...] Private Browsing in Firefox [...]

I have FF version 3.0

I have FF version 3.0 installed without this feature. All i can say, i just don't need it, because I can erase all the private date anytime I want with "clear private data".

Common opinion

nice post! Thanks.

Firefox is missing the boat here...

(Hey, first of all... great post... thanks for taking the time...)

I hate making statements like that (about FF missing the boat) - especially because Firefox when I found it somewhere closely after 2.0, was like heaven sent, a real gift to work with. IE for Mac was (thankfully) being written off by M$ and I tried convincing myself from day one that Safari when it came out was an IE killer when in fact Safari just sucks, it always has (in varying degrees) and chugging along at v.4 (b) isn't dramatically different except it's got the killer developer tools right at your finger tips AND coverflow for bookmarks so it looks like its doomed for inevitable suck-dom.

It'll be a couple years before there's really heated competition... on all levels, as a whole... but with Google Chrome's implementation of private browsing including the "multiple instances"-esque approach and this browsa called Stainless for Mac (a Chrome knock offwhich has had 100% success in the 6 months I've been testing it in effectively submitting masked User Agents - I feel bad for things like Opera that still battle it out one on one with individual websites despite their feature to change User Agent) with it's private browsing & tab specific cookies allowing multiple log ins under different credentials to the same site... I think Firefox made the best decision for the here and now but who knows how long before people smarten up and start to feel the FF implementation is a dumbed down version of PB'ing. And from reading the Mozilla PB wiki https://wiki.mozilla.org/PrivateBrowsing, it sounds like they put a lot of long hard work into it.

And I wonder how PBing will play out in enterprise... I don't know the distribution stats about FF in business, but the majority of Fortune 500 co's expressly forbid browsing that is not work related and usually block a bunch of domains known to suck up your day.

I am terribly thrilled though with the new tear away tabs! I often have my laptop hooked up to my flat screen and will browse for something to watch on it and then have to either drag the whole window which may have other tabs with it over to the TV only to drag it back when video is done or cut n paste url to new window on the TV.

(and a big thumbs down to geolocation - you tell SOMEBODY, ANYBODY who will listen that they have done more harm then good by releasing this pathethic information http://www.mozilla.com/en-US/firefox/geolocation/ which is pretty much standard FF disclosure and business as usual for any feature. It's pathetic because there's absolutely no end-user justification presented AT ALL. Just "talk to a third party about what they are going to do with your information." This isn't like having a cell phone and being lost in the woods and tracked down for rescue by helicopter. It's bad enough IP addresses get submited all over the place. But I'll find another blog to cry about this on.)

Partition Memory

I realize that the data from the browsing session will not be stored in the regular memory of my computer, but will files used by the browser be found in the partition memory if someone were to go looking there?

Re: Partition Memory

I'm not sure what you mean by "partition memory", but in private browsing mode, no personal information will be stored on any part of your hard disk.

No more "clear private data"

I hate it when people come to my house and do something and then click the click private data, they delete my information, now with the feature you described here it solves the problem. I will tell everyone who approaches my computer to wait a second will turn this feature on and will explain what it does and when they go I will disable it.

Thanks for that info

makes me wonder what you let

makes me wonder what you let people use your computer for Oo

Hello, Will there be a button

Hello,

Will there be a button that I can add to the toolbar to enable/disable this feature more quickly than going into the tools menu? I'd like to see this feature.

Lee

Re: Hello, Will there be a button

Yes, such a button is already available using the Toggle Private Browsing extension which I have written about before.

Private Browsing- Mode Indicator Suggestion

There have been many intelligent suggestions on hiding the PB mode from peepig toms while at the same time reminding the user that he is in PB mode or otherwise.

I have a suggestion that may achieve both.
The user can select a thumbnail image from his /her image collection THAT would be his personal cutomized reminder that the user is in private browising mode without anyone suspecting it. ONLY THE USER KNOWS WHAT THAT ICOn / IMAGE MEANS.

This thumbnail can sit as an ICON in the address bar / side bar

Laternatively it can be a part of the web page at a fixed location so that it appears as just one of the images to anyone with passing curiosity.

Since I am not a software engineer, I cannot comment on the technical feasibility of this BUT it should be posssible to implement this.

User can frequently change this image. Obviously the image sgould be some kind of gawdy or eye-candy & not very dull if it to serve this purpose proper

Re: Private Browsing- Mode Indicator Suggestion

Thanks for your feedback!

I'm afraid that with your suggestion, the presence of the icon itself might be an indicator of the private browsing mode being active.  That is, if someone passes by and notices an image in an unusual location, the fact that the image is there is enough for them to tell whether the private browsing mode is active or not.

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[...] habe keine Ahnung, was Du damit meinst. Das ist der neue Firfox Porno-Modus. Hat SM nach nicht. http://ehsanakhgari.org/blog/2008-11...owsing-firefox bye, Sascha -- "Oh Gott im Himmel, der du geschaffen hast die Berge, das Meer, das [...]

Private Browsing

My version of Mozilla is 3.0.8. I do not see the option of enabling private browsing under tools menu. Is it possible that teh administrator would have removed the tool while installation?

Re: Private Browsing

Private Browsing is a feature which will be part of Firefox 3.5, which will be released soon.  To test the feature right now, you need to install a Beta version of Firefox.

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[...] menu. There is a hidden way to make Firefox 3.1 Beta 2 always start in Private Browsing Mode and a plan to possibly provide an easier way to do this in the final 3.5 release, but the only obvious use for [...]

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[...] приватного web-серфинга, когда никакая информация не оседает в кеше браузера, [...]

Will the IT departmetn know which sites I visit through PB?

Hi. I'll throw a question most of you will find a bit stupid. I'm not a techie so I'll just go ahead and shoot the question: Does going PB prevent the IT department from knowing which sites are you visiting?

Safe internet browsing

While PB does help, what you want is to use a proxy server while browsing the web.

Two options:

1. Type the proxy server IP and port into your web browser. (google free proxy servers for free public proxy IPs).

2. Use a proxy server client such as annonymizer.com

This method will allow you to surf all you like whilst using your work computer without the IT team knowing.

Chain proxy

You can also use chain proxy for more anonymity.

Re: Will the IT departmetn know which sites I visit through PB?

Yes, they can monitor your Internet activity if they choose to.

Basically, it's not truth. US

Basically, it's not truth. US government can somehow try t monitor us ISPs, but if you use satellite connection registered anonymously, they can't track you

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